1. Technical Field of the Invention
The present invention relates to an organopolysiloxane and a cosmetic material containing the organopolysiloxane, and relates specifically to an organopolysiloxane having a specific amide group and a cosmetic material containing that organopolysiloxane.
2. Description of the Prior Art
Because of their relative safety and the like, silicone oils such as dimethylpolysiloxanes are used as oil agents in a wide variety of fields. They are also widely used within cosmetic materials, and in applications such as skin care products and makeup products, low-viscosity silicone oils having a viscosity of 100 mm2/s or less are particularly widely used due to their superior extensibility, feeling of freshness, and level of safety.
However, if the silicone oil is the lone oil agent, then the cosmetic material tends to suffer from unsatisfactory adhesion to the skin and inadequate moisturizing properties. As a result, organic oil agents such as hydrocarbon oils, ester oils and plant-based oils are often used in combination with the silicone oil. However, silicone oils, and particularly dimethylpolysiloxanes, are non-polar oil agents, and when combined with high-polarity ultraviolet absorbers, or high-polarity oil agents such as ester oils and natural animal-based or plant-based oils, tend to be prone to phase separation over time, resulting in long-term stability problems.
In order to address this problem, silicones having phenyl groups or long-chain alkyl groups within the molecule (Patent Document 1) and silicones having long-chain alkyl groups and polyoxyethylene groups within the molecule (Patent Document 2) have been proposed as agents for improving the compatibility of silicone oils and organic oil agents. However, cosmetic materials containing these silicones are unsatisfactory in terms of adhesion to the skin, cosmetic retention, and skin affinity properties.
Compounds in which polar groups such as carboxyl groups or amide groups have been introduced into silicones are also known. For example, silicones having a group represented by the formula shown below (Patent Document 3),
silicones having a group represented by the formula shown below (Patent Document 4),—(R1O)a—R2—(OR3)b—COOM(wherein M represents a hydrogen atom, alkali metal or ammonium or the like), and silicones having a group represented by the formula shown below (Patent Document 5)
(wherein X represents —O— or —NH—, and M represents a hydrogen atom, metal or ammonium or the like) are already known. The first and second groups listed above contain a single carboxyl group, and the effect of this polar group tends to be inadequate. The third group contains two carboxyl groups, but the fact that preparation of the silicone requires a special amine compound is problematic.
In contrast, acid anhydride-modified silicones can be prepared comparatively easily (Patent Document 6), and amide-modified silicones obtained by reacting such acid anhydride-modified silicones with amines are already known (Patent Document 7). However, these amide-modified silicones are unsatisfactory in terms of factors such as compatibility with the oil agents mentioned above and skin affinity.
Further, because silicone oils such as dimethylpolysiloxanes also have a light feeling, exhibit excellent water repellency and offer superior safety, they are widely used in cosmetic materials. However, silicone oils tend to suffer from sensory type problems, including exhibiting poor affinity with the skin and imparting a slight abrasive feeling to the skin.
In order to improve these types of poor sensory properties that are inherent to silicones, hydrophilic groups are introduced into the silicones. For example, various glycerol-modified silicones are known (for example, see Patent Document 8). Incorporating glycerol-modified residues reduces the slight abrasive feeling of the silicone. However, these glycerol-based oil agents tend to impart a characteristic stickiness, and are also unsatisfactory in terms of the durability of the cosmetic film that is produced.
Silicones in which amide groups have been introduced as hydrophilic groups are also known. For example, Patent Document 3 discloses a silicone having a group represented by the formula shown below,
Patent Document 5 mentioned above discloses a silicone having a group represented by the formula shown above, and Patent Document 7 mentioned above discloses a polysiloxane having carboxyl groups in which 50% of those carboxyl groups have undergone amidation using 2-amino-2-methyl-1-propanol, ethanolamine, morpholine or triethanolamine. These compounds are useful as surfactants for aqueous compositions used for cleaning or the like, but are not entirely satisfactory in terms of the feeling produced when applied to the skin.